Oil compositions containing aluminum disoap and an amine



United States Patent Office 3,010,90 Patented Nov. 28, 1961 3,010,900 OIL COMPGSITIUNS CGNT IN ALUM DEQAP AND AN Hugh H. Horowitz, Elizabeth, and Eric 0. Forster, Scotch Plains, NJ, assignors to Esso Research and Engineering Company, a corporation of Delaware N Drawing. Filed May 19, 1958, Ser. No. 735,932 7 'tilahns. (Cl.25237) This invention relates to an additive system for improving the viscosity-temperature characteristics of lubricating Oil. Particularly, the invention relates to lubricating oil compositions containing a combination of aluminum soap and an amine for improving the viscosty index (V.I.) of the composition.

Recently there has been a marked growth in the use of 'multi-grade lubricating oils for automotive lubrication.

These oils contain V.I. improving additives which minimize the viscosity change of the oil with temperature thereby permitting the use of the same oil over a wide temperature range. This viscosity change in commercial multi-grade oils is usually regulated by high molecular weight polymers such as polymethacrylates and polyisobutylene. However, these long chain polymers tend to irreversibly break down into smaller chains in actual crankcase use. In fact, the chains are literally sheared by the moving parts of the engine and their eifectiveness is permanently decreased upon use. It had been known that aluminum hydroxy disoaps tend to associate together to form long chains, somewhat akin to those of the previously described polymers. However, it had not been possible to make effective use of these long chain aluminum soaps for purposes of regulating the viscosity-temperature relationship of lubricating oil. Thus, these aluminum disoaps form extremely long chains which produce a gelling effect upon the oil, and in large concentrations will actually form solid greases. If an attempt is made to form a fluid lubricant by reducing the concentration of the aluminum disoap in oil, then phase separation occurs and a non-homogeneous system results. It has now been found that by using the aluminum disoap in conjunction with certain amines it is possible to effectively regulate the length of the aluminum disoap chain and to improve substantially its V.I. improving powers. Thus, the gelling elfect is inhibited and at the same time the disoap chains will function more like the aforementioned long chain hydrocarbon polymers in regulating the viscosity index of lubricating oils. Not only is no gel formed at lower temperatures but the thickening effect of the amine-disoap system is actually less at low temperatures than at high temperatures.

One important advantage of the aluminum disoap chains is that they do not show any substantial permanent shear breakdown, clue to the unique ability of the soap chains to reform themselves if broken. In fact, there may be a continuous equilibrium between the formation and rupture of chain links when the disoap is in oil solution. This unique ability of reformation permits extended use of the oil composition without the loss of viscosity-temperature characteristics. Another advantage of the present additive system is that in addition to the V.I. improving function, both the aluminum disoap and the amines function as oil detergents.

The aluminum hydroxy disoaps operable in this invention are formed from straight or methyl-branched, saturated and unsaturated, unsubstituted monocarboxylic acids which preferably contain about 8 to 12 carbon atoms per molecule, e.g. fatty acids such as octanoic, nonanoic, lauric acid, etc. Chain lengths less than 8 carbon atoms are not too desirable since they result in soaps unduly soluble in the oil, while longer chain lengths result in too great a thickening effect.

The amines oper- 2 able for limiting or blocking the aluminum disoap chain are those -having the general formula:

wherein R is an aliphatic, straight or branched hydrocarbon radical which may be ether interrupted, and contains a total of 1 to 22, preferably 8 to 18, carbon atoms; R is preferably hydrogen, or a short alkyl group such as a methyl radical, and R" can be the same as R or R.

The disoap and the amine are used together in ratios such that there is about .01 to 1.0, e.g. .2 to .5 part by weight of the amine per one part by weight of the aluminum disoap. In turn, this additive combination, i.e. disoap and amine, can be used in finished lubricating oils in amounts of 0.5 to 10, e.g. 1.5 to 3.5 weight percent, based on the total weight of the oil composition. For

. ease of handling, oil concentrates of these additives may also be prepared which may contain 5 to 30 wt. percent additive.

The lubricating oils which can be improved in their viscosity index by the above described additive combination will include mineral lubricating oils, synthetic lubricating oils, or mixtures thereof. Synthetic lubn'cating oils which may be used include esters of dibasic acids {c.g. di-Z-ethylhexyl sebacate); esters of glygols (e.g. C Oxo acid diester of te-tnaethylene glycol); complex esters e. g. the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of Z-ethylhexanoic acid); formals; silicones; carbonates; polyglycols and other synthetic lubricating oils known in the Although of primary advantage for use in lubricating oils intended for automotive crankcase use, the additive combination of the invention may be used in other oil compositions, such as: turbine oils, industrial oils, oils for atomic installations, hydraulic and transmission fluids, heating oils, etc.

In evaluating the efiectiveness of the additive systems of the invention in improvi g the viscosity-temperature characteristics of lubricating oil two criteria were used.

One criteria was the common Dean and Davis Viscosity Index relationship which is fully described in A.S.T.M. D-567. This relationship is :as follows:

where U is the viscosityat F. of the oil under consideration. I

In order to apply the above formula, the viscosities of the oil under consideration at 100 F. and 210 F. must be determined, and may be expressed in either centistokes or in Saybolt Universal seconds. Values for L and H are taken from tables. I

Although the Dean and Davis V.I. scale is widely used to express numerically the viscosity-temperature relationship for an oil, it is not too well suited for use in the range of V.-I., the range of interest here, because of anomaly in the V1. system and because the V1. level is sharply dependent on the viscosity level at which the measurement is made.

Therefore in an attempt to more effectively evaluate the viscosity-temperature relationships imparted by the 3 additive systems of the invention, a second relation was used which consisted of the following equation;

wherein:

S is a numerical value expressing the rate of change of viscosity with temperature. Thus, the lower the value of S, the less the additive thickens at lower temperature and the better the oil composition in this respect.

Sp 100 F. is the increase in viscosity in centistokes at 100 F. contributed by the additive, divided by the viscosity of the base oil in centistokes at 100 ,F. That U 1 blendnbase oil 100 base oil Sp 210 F. is a ratio similar to nSp 100 F., except that the viscosities are obtained at 210 F.

A series of lubricating oil blends were prepared by simple mixing of an aluminum hydroxy di-n-octanoate and various amine blocking agents in a solvent extracted mineral lubricating oil containing bright stock. The

amines used were: lauryl dimethyl amine, n-octyl amine,

Primene J MT (Rohm and Haas) which is a tertiary alkyl primary amine having predominantly 18 carbon atoms per molecule with minor amounts of homologous molecules of 19 to 24 carbon atoms, Amine 9D-178 (Rohm and Haas) which is a mixture of highly branched unsaturated secondary aliphatic amines having an average molecular weight of 375, and Alkyl Ether Amine #1 (Archer-Daniels-Midland), which has the formula:

groups containing 14 and 16 carbon atoms each, derived from commercial lauric acid.

The exact compositions prepared and their viscositytemperature relationship are given in Table I which follows:

As seen from the preceding table, the base oil had an initial V.I. (Dean and Davis) of 107. The addition of 1 wt. percent of aluminum dioctanoate (A) resulted in an S value of 0.606 and a V1. of 140. However, at 77 F. this composition formed a gel, i.e. a grease-like material, due to the unregulated thickening efiect of the aluminum disoap. The addition of the lauryl dimethyl amine (B) eliminated the gelling effect of the disoap, while further lowering the S value. The n-octyl amine (C), the Primene JMT (D) and Amine 9D-178 (B) were also efrectivewith the aluminum disoap, although they did show a slight gelling effect at 77 F. This slight gelling effect was not too serious since it can be removed and a homogeneous product formed by milling the composition, e.g. by passing the composition through a Morehouse mill or a Gaulin homogenizer.

The alkyl ether amine #1 (F) was quite effective, showing no gelling tendency and a very low S value, although it should be noted that this value is not too precise, being the ratio of two small numbers. Compositions G, H and 1 illustrate the use of larger amounts of the disoap, and here again it is seen that the lauryl dimethyl amine and the alkyl ether amine #1 were both quite efiective in preventing gelling while at the same time maintaining a good viscosity-temperature relationship.

EXAMPLE II Table II VISCOSITY-TEMPERATURE CHARACTERISTICS OF BLEN DS OF ALUMINUM DIDECANOATE AND ALKYL ETHER AMINE #1 IN OIL Al soap Alkyl cone, ether Vie/20 VisJlOO Vis./2l0 weight amine #1 1 (cs.) (05.) (cs) P v.1. percent weight 1 51) 210 percent 0. 2 469. 9 32. 10 5. 36 111. 5 0. 4 462. 5 3 31. 50 5. 26 110 1. 0 O. 2 548. 6 44. 79 9. 01 154 0. 3 496. 3 38. =16 7. 36 147 0. 4 489. 5 33. 39 6. 02 134 0. 8 468.0 31. 5. 39 114 1. 5 O. 4 710.0 52. 11 11. 76 159. 5 O. 6 573. 1 B7. 92 7. (i2 152. 2 0. 8 472. 6 32. 31 5. 60 123 2. 0 0. 8 632. 0 42. 24 9. 98 164 1 ROGHZOHZOHQNHQ where R represents alkyl radicals derived from 55 commercial lauric acid.

7 Table I V BLENDS OF Al DIOOT ANOATE AND VARIOUS AMINES IN MINERAL 'LUBRICATING OIL C 1 Aluniig r S= V.I.

ompos num Vls./ Vis. S S S- 100 D an .11 g tion octanoate Weight percent blocking agent 210 F 100 21 0 13 100925. 210 arid iire ii weight cp. cp. Davis) at 77 F percent 0.0 9.51 79.96 101 None 1.0 16. 58 115.9 0. 741 449 606 140 Yes. 1. 0 16. 70 106. 7 .7 57 332 439 1.40 None. 1.0 28.35 166.3 1; 980 1.072 .542 136 Slight 1. 0 25.6 180. 7 1.493 1. 258 843 133 Do. 1.0 20.:05 150. 2 1.11 .879 792 111 D0. 1.0 9.88 80.65 .0305 .0086 .280 141 None 2. 0 0 34. 30 245. 4 2. 61 2. 064 792 Yes. 2.0 0.4 lauryl dimethyl amine 37. 74'. 181. 9 2. 97 1. 275 429 142 None. 2. 0 OA alkyl ether amino #1,. .13. 70 98. 6 442 233 .528 131 D0.

1 Mixture of Ora-2 tertiary alkyl primary amines. v

1 Mixture ofhighly branched-chain secondary aliphatic amines, average molecular weight of 375. a EOOH OE CH NH where R represents alkyl radicals derived from commercial lauric acid.

6 As seen from Table II, better and better S values viscosityatemperature characteristics of lubricating oil were obtained as the concentration of aluminum disoap compositions. and amine blocking agents were increased. The S What is claimed is:

values below 0.6 are superior to those obtainable with 1. A liquid lubricating oil composition comprising a the best commercial V.I. improver. The aluminum dimajor proportion of a lubricating oil and about 0.5 to soap alone in the oil and without the amine would have 10.0 wt. percent of an additive combination of aluresulted in solid gels at 20 F., even at a concentration minum hydroxy disoap of a C to C fatty acid and of 0.5 Wt. percent disoap. However, with the blocking about 0.01 to 1.0 part by weight of an amine per part agent present the viscosity of the blend is only slightly by weight of said aluminum disoap, wherein said amine higher than the base oil at 20 F. has the general formula:

EXAMPLE III A third series of compositions were prepared by simple l mixing of aluminum hydroxy di-n-decanoate and lauryl dimethyl amine in varying amounts in a solvent extracted mineral oil containing bright stock The compositions tested and their properties are summarized in Table III.

wherein R contains a total of about 1 to 22 carbon atoms and is selected from the group consisting of alkyl radi- Table I cals and ether interrupted alkyl radicals, R is selected from the group consisting of hydrogen and methyl ALUMINUM ggfi figg gt gg g gg DIMETHYL radicals and R" is selected from the group consisting of R and R and wherein said aluminum hydroxy disoap VL is the sole aluminum soap. dnsurn dimethyl x35 10X6s 5. 4 5 Da h 2. The l quid lubr cating oil composition of claim 1, high f 1781, 210 Dfiis) wherein R and R 'both represent hydrogen and R percent) percent) 25 represents an alkyl radical.

3. The liquid lubricating oil composition of claim Alumi- Lauryl 0.0 0.0 111.8 11. 92 104.5 1, wherein R and R" both represent hydrogen and R if 83% 2:338 fig Egg 8&2 fig represents an ether interrupted alkyl radical. 1 0 4. The lrqu d lubricating composition of claim 1, '1'?" 37280 50 0. H 134 wherein said lubricating oil is a mineral oil. 0.6 w 275.10 47.94 0. 443 137 5. The liquid lubricating oil composition of claim 1,

wherein said fatty acid is a C fatty acid. EXAMPLE IV 6. A method of lubricating an automotive piston en- A series of oil compositions were prepared by mixing Whlch P operanng 531d eng1ne W1t-h t an aluminum disoap prepared from the saturated C 1308mm m crankcase Qi fi- C fraction of cocoanut fatty acids and either lauryl A 1'1qu1d 1ubnatmg 011 PP W {Ompnsmg a dimethyl amine or alkyl ether amine #1 in a neutral major P P of a mineral h lbrl catlllg 011 and afbollt pa ajfinic mineral lubricating The co npositions 1.5 t0 Wt. percent Of a combination Of an aluminum prepared and their viscosity-temperature characteristics Y Y diSOaP Of a 6 to 12 fatty add and about are summarized in Table IV which follows: 40 to 0.5 parts by weight of an amine per part by weight Table IV ALUMINUM DISOAP PREPARED FROM GOOOANUT FATTY ACID AND AMINES IN MINERAL LUBRICATING OIL Al. Amine, Vis./ Vis. S disoap, weight 20 F. 100 F. 210 F. Sp 100 F. V.I. weight percent (cs) (05.) T

percent Base Oil O 0 458. 2 31. 74 5. 30 110 Lauryl d'unethyl amine 1. 0 0.2 498. 5 43. 8. 80 0. 567 154 Alkyl ether amino #1 1. 0 0. 2 548. 6 44. 79 9.01 0. 587 154 Lauryl dimethyl amine- 1. 5 0. 4 490. 4 127. 30 22. 0. 920 144 0 Alkyl ether amino #1 1. 5 0. 4 710.0 52. 11 11.76 0.527 159 1 The coccauut fatty acid consisted of a mixture of about 28 weight percent caprylie, 56 weight percent capric and 16 weight percent lauric acids.

EXAMPLE V of said aluminum disoap, wherein said amine has the general formula:

A composition was prepared consisting of 98.1 Wt. percent mineral lubricating oil of 170 SUS. at 100 F., 69 l 1.5 wt. percent of aluminum hydroxy disoap of cocoanut RTIFI fatty acid, (same as in Example IV) and 0.4 wt. perg R cent of alkyl ether amine This Composition was wherein R contains 8 to 18 carbon atoms and is selected tested in actual lubricating use in a laboratory Chevrolet f the gmup consisting f alkyl .nadicals and ether Gilgine- This test inVOlVfid a -cylinder engine running 6 terrupted alkyl radicals and R and R" represent hydro under moderate constant speed and load conditions for 24 hours. T he engine stood. for another 24 hours before the oil was drained and dismantling began. Oil samples were removed at frequent intervals to follow References Cited in the file of this patent UNITED STATES PATENTS the change in viscosity. At the end of the test, the 70 2,320,002 Lutz et a1. May 25, 1943 engine appeared very clean and no gelling of the oil had 2,491,641 B'ondi Dec. 20, 1949 occurred. 2,758,086 Stuart et al. Aug. 7, 1956 'In summary, this invention relates to an additive combination of an aluminum disoap and certain amines. FOREIGN PATENTS I 563,429 Great Britain 1 Aug. 15, 1944 This combination is extremely efiective in improving the 

1. LIQUID LUBRICATING OIL COMPOSITION COMPRISING A MAJOR PROPORTION OF A LUBRICATING OIL AND ABOUT 0.5 TO 10.0 WT. PERCENT OF AN ADDITIVE COMBINATION OF ALUMINUM HYDROXY DISOAP OF A C8 TO C12 FATTY ACID AND ABOUT 0.01 TO 1.0 PART BY WEIGHT OF AN AMINE PER PART BY WEIGHT OF SAID ALUMINUM DISOAP, WHEREIN SAID AMINE HAS THE GENERAL FORMULA: 